logit: Generalized logit and inverse logit function

In gtools: Various R Programming Tools

Generalized logit and inverse logit function

Description

Compute generalized logit and generalized inverse logit functions.

Usage

logit(x, min = 0, max = 1)

inv.logit(x, min = 0, max = 1)

Arguments

x	value(s) to be transformed
min	Lower end of logit interval
max	Upper end of logit interval

Details

The generalized logit function takes values on [min, max] and transforms them to span [-Inf,Inf] it is defined as:

y = log(\frac{p}{(1-p)})

where

p=\frac{(x-min)}{(max-min)}

The generalized inverse logit function provides the inverse transformation:

x = p' (max-min) + min

where

p'=\frac{exp(y)}{(1+exp(y))}

Value

Transformed value(s).

Author(s)

Gregory R. Warnes [e-mail]

See Also

logit

Examples

x <- seq(0, 10, by = 0.25)
xt <- logit(x, min = 0, max = 10)
cbind(x, xt)

y <- inv.logit(xt, min = 0, max = 10)
cbind(x, xt, y)

gtools documentation built on Nov. 20, 2023, 5:07 p.m.